Incandescent lamp



Patented Dec. 22, 1925. y

V 1,566,848 UNITED STATES PATENT OFFICE.

GOBTON B. IONDA, OF SCHEKEC'IADY, NEW YORK, ASSIGNOB TO GENERAL ELECTRIC COHPNY, A CORPORATION 01 NEW YORK.

INCANDESCENT Lam!- N0 Drawing.

To all whom g't may concern:

Be it known that I, GOR'ION R. F ONDA, a citizen of the United States, residing at- Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Incandescent Lamps, of which the following is a specification.

The present invention relates to electric incandescent lamps. It is the object of my invention to improve their efiiciency and life.

During the operation of an incandescent lamp, particularly lamps containing a filling of inert gas, discoloration of the bulb may sometimes occur early in the life of the lamp, which appears to be due to some cause other than expected gradual evaporation of the filament material at the high operating temperature.

Investr ations indicate that this discoloration is ue to gases, particularly water vapor, evolved from the glass bulb and perhaps also other interior parts of the lamp. Water appears to be held so tenaciously by glass that some of it is retained even when the glass bulb is baked during its manufacture. These small quantities of water vapor exert a deleterious eflect on the filament or glower in the lamp and cause its disintegration. Moisture also may arise from chemical combination between hydrogen introduced in any way, as for example with the gas filling, with oxides also inadvertently introduced into the lamp.

I have discovered that the introduction into the bulb of a material which contains carbon, for example, acetylene gas, suppresses this early discoloration of the bulb, and besides improves the physical properties of the incandescent body.

The benefits of my invention are not lim ited to the utilization of a gaseous carbonaceous material. Free carbon in a finely divided condition may be applied to the exterior of the filament, as described and claimed in an application, Serial No. 540,- gilll, filed March 2, 1922, by Percy A. Camp- In accordance with one method of carrying out my invention, a small quantity of carbonaceous gas is introduced into the lamp, preferab y after the tungsten filament, or other glower, has been mounted therein. Besides acetylene, Q 11 v'a'rious hydrocar Application filed January 26, 1922. Serial no. 532,044;

bon gases may be used, for example, methane, CI-L, naphthalene vapor, G lf-I anthracene vapor (J,, H or the like. Preferably, a material wmcli does not containbothoxygen and hydrogen is employed, as the latter libcrate an excessive amount of water vapor by its decomposition.

The amount of carbon as an elementary constituent introduced into the bulb should be limited to substantially no more than about one to two-tenths (0.1 to 0.2%) of the weight of the incandescent body and preferably the amount of carbon should be materially less-than this amount, say, five-hum dredths of one per cent (05%) of the lighting body by weight. A portion of the carbon may combine very early in the life of the lamp with water vapor or other deleterious ox genous gases, but in any event the amount mitially introduced should be insufficient to decrease the lighting efiiciency of the glower.

After the acetylene, or other carbon-containing material, has been introduced into the bulb, the usual gas filling may be'admitted, as for example, argon or nitrogen gas at a pressure a little below atmospheric pressure. In case the bulbs are sealed off while containing only the carbon-containing gas, they will remain essentially vacuum lamps, particularly so as the gas is quickly decomposed by the and in any event has a pressure of less than fifty )microns of mercury pressure (0.050 m.m-

If desired, carbon may be introduced into the filament by incandescing the filament in the presence of a carbonaceous vapor of suitable composition and..pressure and when a desired amount of c v n has been deposited on the filament mounting the same in a bulb. Carbon is introduced thereby into the lamp in such a manner as to be heated in contact with the gase in the lamp to a temperature of chemical activity by the normal incandescence of the filament.

The addition of the carbon-containing gas to the lamp" decidedly improves the strength of an incandescent body consisting of duetile tungsten. The ductility and resistance to sag of the metal also are improved. These mechanical improvements in my opinion are due to the removal by chemical action of mpurities betweenthe grains'of the metal.

The average life of lamps embodying my inincandescent filament,

vention is longer than lamps operating at the same efliciency but unprovided with carbon in a condition adapted to combine with deleterious impurities in the lamp.

In accordance with an invention of Carl T. Fuller described in an application, Serial No. 532,047, filed January 26, 1922, an organic dye is placed in incandescent lamps to provide a visible record of the temperature attained during the manufacture of the lamp. As various dyes suitable for this purpose have an appreciable vapor pressure' articularly at the operating temperature 0 the lamp, they will serve the added purpose of furnishing carbon for the purposes of my invention. Various dyes of the aromatic or benzene ring series may be used for this purpose, for example, dyes belonging to the triphenyl methane group, such as malachite green and methyl violet.

When in accordance with the above mentzoned application Serial No. 540,611 free carbon is introduced into the lamp, it may be applied by spraying the filament 'wit a suspension of carbon, as for example, with a suspension of aquadag in water. I desire by the appended claims to cover all the above described improvements and other modifications of my invention.

What I claimas new and desire to secure by Letters Patent of the United States, is,-

1. An electric lamp comprising the com bination of an incandescent body of refractory metal, a sealed bulb, a carbon-containing material in said bulb available for chemical reaction with gases in said bulb at the operating temperature of said body and in such quantity that by combination thereof with impurities in said lamp the operating properties of said body are improved.

2. An incandescent lamp comprising the combination of an incandescent bod of tungsten, a sealed bulb, a filling of gas t lerein inert with respect to tungsten at incan descence and a quantity of a gaseous compound of carbon in quantities sufficient to materially suppress bulb discoloration at the beginning of the life of said lamp, but in sufficient to deleteriously affect'said incan descent body.

3. An electric lamp comprising the combination of a sealed container, a refractory lighting body therein, and a quantity of carbonaceous material in said container located with respect to said body as to be heated to a temperature of chemical activity, while in contact with gas residues in said lamp, the amount of carbon being limited to about five-hundredths of one per cent of the weight of the lighting body but'sufiicient i n quan tity to suppress premature discoloration of the bulb.

4. An electric device comprising the combination of a sealed glass ulb, a lightin body therein .consisting of refractory meta and a quantity of carbonaceous material in said bulb within the heating zone of said body, said material being ca able of introducing no more than about ve-hundredths of one per cent of carbon into said body.

5. An incandescent lamp comprising a sealed bulb, a metal filament therein and a quantity of carbonaceous material so placed with respect to said filament that under the operating conditions of the lamp said material is capable of combining chemically with deleterious gases given off by the bulb or other parts of said lamp, thereby reducing premature discoloration and improving the physical condition of said filament.

6. An incandescent lamp comprising a sealed bulb, a refractory metal filament and a quantity of carbonaceous material therein in contact with said filament during the operation of the lamp, capable of forming substantially no more than about one to twotenths per cent of combined carbon in said filament.

7. An electric lamp comprising the combination of a sealed container, 9. refracto metal body therein capable of reacting wit carbon at incandescence, and a quantity of carbon-containing vapor in said device adapted to introduce about three-hundredths of one per cent of carbon into said metal body.

8. The method of preventing the premature blackening of lamps containing a metal filament which consists in introducing into the filament a material which is capable of combining with water vapor, the quantity of said material being insuflicient to materially aiiect the constitution of said filament, and heating said material to the reactive temperature by the normal operation of said lamp.

9. The method of improving the operation of a tungsten incandescent body in a lamp which consists in introducing into contact with said body at incandescence, gaseous carbonaceous material in sufficient amount to combine with deleterious gases but insuflicient to decrease the lighting etficiency of said lamp.

In witness whereof, I have hereunto set my hand this 25th day of January, 1922.

GORTON R. FONDA. 

